Method of recording sonar data

ABSTRACT

A sonar system comprising a sonar transmitter, a very large array two dimensional sonar receiver, and a beamformer section transmits a series of sonar pings into an ensonified volume of fluid at a rate greater than 5 pings per second, receives sonar signals reflected and scattered from objects in the ensonified volume, and beamforms the reflected signals to provide a video presentation and/or to store the beamformed data for later use. The parameters controlling the sonar system are changed so that the beamformer section treats the data from the receiver section with more than one set of parameters per ping and/or neighboring pings. The stream of data is treated either in parallel or in series by different beamforming methods so that at least one beam from the beamformer has more than one value.

RELATED PATENTS AND APPLICATIONS

The following US Patents and US patent applications are related to thepresent application: U.S. Pat. No. 6,438,07 1 issued to Hansen, et al.on August 20; U.S. Pat. No. 7,466,628 issued to Hansen on Dec. 16, 2008;U.S. Pat. No. 7,489,592 issued Feb. 10, 2009 to Hansen; U.S. Pat. No.8,059,486 issued to Sloss on Nov. 15, 2011; U.S. Pat. No. 7,898,902issued to Sloss on Mar. 1, 2011; U.S. Pat. No. 8,854,920 issued to Slosson Oct. 7, 2014; and U.S. Pat. No. 9,019,795 issued to Sloss on Apr. 28,2015; U.S. patent applications Ser. Nos. 14/927,748 and 14/927,730 filedon Oct. 30, 2015, 15/978,386 filed on May 14, 2018, 15/908,395 filed onFeb. 28, 2018, 15/953423 filed on Apr. 14, 2018, 16693684 filed Nov 11,2019, and 62931956 and 62932734 filed Nov. 7, 2019, 16/362255 filed onMar. 22, 2019, and 62/818,682 filed Mar. 14, 2019 and 16/727,198 filed26 Dec. 2019 and are also related to the present application. The aboveidentified patents and patent applications are assigned to the assigneeof the present invention and are incorporated herein by reference intheir entirety including incorporated material.

FIELD OF THE INVENTION

The field of the invention is the field generating and receiving ofsonar pulses and of visualization and/or use of data from sonar signalsscattered from objects immersed in a fluid.

OBJECTS OF THE INVENTION

It is an object of the invention to improve visualization using sonarimaging. It is an object of the invention to measure and record thepositions and orientations, and images of submerged objects. It is anobject of the invention to improve resolution of sonar images. It is anobject of the invention to present sonar video images at increased videorates. It is an object of the invention to rapidly change the sonarimage resolution between at least 2 pings of a series of pings. It isthe object of the invention to change rapidly change the direction ofthe field of view on sonar images between at least 2 pings of a seriesof pings.

SUMMARY OF THE INVENTION

A series of sonar pings are sent into an insonified volume of water andreflected or scattered from submerged object(s) in the insonified volumeof water. One or more large sonar receiver arrays of sonar detectors areused to produce and analyze sonar data to produce 3 dimensional sonardata describing the submerged object(s) for each ping. One or moreparameters controlling the sonar imaging system are changed betweenpings and/or within a single ping in the series of pings. The resultingchanged data are stored and/or combined together to produce an enhancedvideo presentation of the submerged objects at an enhanced video framerate of at least 5 frames per second. More than one of the parametersused to control the sonar imaging system are used to produce different3D images from the same ping in a time less than the time between twopings.

DETAILED DESCRIPTION OF THE INVENTION

It has long been known that data presented in visual form is much betterunderstood by humans than data presented in the form of tables, charts,text, etc. However, even data presented visually as bar graphs, linegraphs, maps, or topographic maps requires experience and training tointerpret them. Humans can, however, immediately recognize andunderstand patterns in visual images which would be difficult for eventhe best and fastest computers to pick out. Much effort has thus beenspent in turning data into images.

In particular, images which are generated from data which are notrelated to light are often difficult to produce and often require skillto interpret. One such type of data is sonar data, wherein a sonarsignal pulse is sent out from a sonar generator into a volume of seawater or fresh water of a lake or river, and reflected sound energy fromobjects in the insonified volume is measured by a sonar receiver.

The field of underwater sonar imaging is different from the fields ofmedical ultrasonic imaging and imaging of underground rock formationsbecause there are far fewer sonar reflecting surfaces in the underwaterinsonified volume. Persons skilled in the medical and geological artswould not normally follow the art of sonar imaging of such sparsetargets. The system of the invention-has vessel apparatus of theinvention on the surface of a body of water which we will call a part ofa sea. The water rests on a seabed. It is understood that any fluid thatsupports sound waves may be investigated by the methods of the presentinvention. The apparatus generally comprises a sonar ping transmitter(or generator) and a sonar receiver, but the sonar transmitter andreceiver may be separated for special operations. Various sections ofthe apparatus are each controlled by controllers which determineparameters required for optimum operation of the entire system. In thepresent specification, a parameter is a specific value to be used whichcan be changed rapidly between pings. The parameters may be grouped insets and the set can be switched, either by hand or automaticallyaccording to a criterion. The decision to switch parameters may be madeby an operator or made automatically based on information gained fromprior pings sent out by sonar transmitter or by information gained fromthe current ping. The sonar transmitter sends out pulses of sound waveswhich propagate into the water in an approximately cone shaped beam. Thepulses strike objects in the water such as stones on the seabed, anunderwater vessels, swimming divers, sea wall. The underwater vessel mayeither be manned or be a remotely operated vessel (ROV). The objectsunderwater that have a different density than the sea water reflectpulses 19 as a generally expanding waves back toward the apparatus ofthe invention.

The term “insonified volume” is known to one of skill in the art and isdefined herein as being a volume of fluid through which sound waves aredirected. In the present invention, the sonar signal pulse of soundwaves is called and defined herein as a ping, which is sent out from oneor more sonar ping generators or transmitters, each of which insonifiesa roughly conical volume of fluid. A sonar ping generator is controlledby a ping generator controller according to set of ping generatorparameters. Ping generator parameters comprise ping sonar frequency,ping sonar frequency variation during the ping pulse, ping rate, pingpulse length, ping power, ping energy, ping direction with respect aping generator axis, and 2 ping angles which determine a field of viewof the objects. A ping generator of the invention preferably has a fixedsurface of material which is part of a sphere, but may shapeddifferently.—A ping generator cross section has piezo electricelements-sandwiched between electrically conducting materials. The piezoelectric elements have electrically insulating material separating eachelement from the other elements. One electrically conducting material ispreferably a solid sheet of material which is grounded and is in contactwith the seawater, and is thin enough that ultrasonic pressure waves caneasily pass through it, but thick enough that water does not leakthrough it and get into the interior of the ping generator. The otherend of each of the piezoelectric material elements is energized byapplying an ultrasonic frequency voltage to electrical elements whichare separated electrically from each other and which energize groups ofpiezo electric elements to vibrate with the same phase and frequency.Different segments change the beam pattern of the outgoing sonar waves.The-full beam has a divergence of 50 degrees and the restricted beam hasa divergence of 25 degrees. By energizing appropriate combinations ofelectrodes, the beam may be sent out up, down, left, or right.

Ping generators of the prior art could send out a series of pings with aconstant ping frequency during the ping. Ping frequencies varying intime during the sent out ping are known in the prior art. Changing theping frequency pattern, duration, power, directions, and other pingparameters rapidly and/or automatically between pings in a series hasnot heretofore been proposed. One method of the invention anticipatesthat the system itself uses the results from a prior ping can beanalyzed automatically to determine the system parameters needed for thenext ping, and can send the commands to the various system controllersin time to change the parameters for the next ping. When operating in awide angle mode at a particular angle and range, for example, a newobject anywhere in the field of view can signal the system controllersto send the next outgoing ping the direction of the object, decrease thefield of view around the new object, increase the number of pings persecond according to a criterion based on the distance to the object, setthe ping power to optimize conditions for the range of the object, etc.Most preferably, the system can be set to automatically change any orall system parameters to optimize the system for either anticipated orin reaction to unanticipated changes in the environment.

In a particularly preferred embodiment, the controller system may be setto change the sent out frequency alternately between a higher and alower frequency from ping to ping. The resulting images alternatebetween a higher resolution and smaller field of view for the higherfrequency, and a lower resolution and a larger field of view for thelower frequency. The alternate images may then be stitched after thereceiver stage to provide a video stream at half the frame rate of thesystem available with unchanged parameters, but with higher centralresolution and wider field of view, or at the same frame rate bystitching neighboring images.

The sonar receiver of the invention is a large array of pressuremeasuring elements. The sonar receiver is controlled by a sonar receivercontroller according to set of sonar receiver parameters. The array ispreferably arranged as a planar array because it is simpler toconstruct, but may be shaped in any convenient form such as a concave orconvex spherical form for different applications. The array haspreferably 24 times 24 sonar detecting elements, or more preferably 48times 48 elements, or even more preferably 64 time 64 detectors, or mostpreferably 128 times 128 elements. A square array of elements ispreferred, but the array may be a rectangular array or a hexagonal arrayor any other convenient shape. The detector elements are generallyconstructed by sandwiching a piezo electric material between twoelectrically conducting materials as shown for the sonar transmitter,but with an electrical connection to each element in the array. When areflected sonar ping reaches the sonar detecting element, the element iscompressed and decompressed at the sonar ping frequency, and produces ananovolt analog signal between the electrically conducting materials.The nanovolt signals are amplified and digitally sampled at a sonarreceiver sampling rate controlled by the sonar receiver controller, andthe resulting digital signal is compared to a signal related to sent outping signals to measure the phase and amplitude of the incoming sonarsignals for each receiver element. The amplification or gain for theincoming sonar signals is controlled by the sonar receiver controller.If the sonar ping frequency is changed rapidly between pings, thesampling rate may also be changed to reflect the changed ping frequency.The incoming sonar ping is divided into consecutive slices of time,where the slice time is related to the slice length by the speed ofsound in the water. A slice time parameter is set by the sonar receivercontroller. For example, pings arriving from more distant objects canhave wider slices than pings reflections from closer objects. Each slicecontains a number of sonar wavelengths as the pulse travels through thewater. The sonar receiver preferably has sonar receiver parameterscontrolled by the sonar receiver controller to have, for example,programable phase delays between the detector elements digital samplingtimes may be varied to achieve the same result. The sonar receiver mayhave parameters controlled by the sonar receiver controller which can beset to change the amplification or gain of the nanovolt electricalsignals during the incoming sonar ping reflected signals. Prior art timevarying gain (TVG) systems have used preplanned amplification ramps tocorrect for attenuation in the water column. This gain is applied basedon range (distance from transmitter), but the gain profile does notchange from ping to ping. Generally, the attenuation of the ultrasonicwaves is higher for higher ping frequencies. Prior art changed theamplification factor by a preplanned schedule to even out the signalsbetween the received first slice and the last slice of a ping. Prior TVGdid not allow for the increased absorption by soft mud on the seafloor,for example. Since mud absorbs sound waves, the reflected sound wavesare less intense as soon as the reflected slice reaches the mud. The TVGis changed on the next ping to boost the signals that reflect or arescattered by the mud. In the same way, the TVG is changed to boost orreduce the gain for slices that more strongly reflect or are scatteredby a hard, highly reflecting object like sea wall.

A phase and amplitude of the pressure wave coming into the sonarreceiver is preferably assigned to each detector element for eachincoming slice, and a phase map may be generated for each incomingslice. A phase map is like a topographical map showing lines of equalphase on the surface of the detector array. Applying additional gaincontrol can be incorporated with Phase Filtering.

Phase map and data cleanup and noise reduction may be done optionally inthe sonar receiver or in a beamformer section. The phase map and/or thedigital stream of data from the detector are passed to the beamformersection, where the data are analyzed to determine the ranges andcharacteristics of the objects in the insonified volume.

The range of the object is determined by the speed of sound in the waterand the time between the outgoing ping and the reflected ping receivedat the receiver. The data are most preferably investigated by using aspherical coordinate system with origin in the center of the detectorarray, a range variable, and two angle variables defined with respect tothe normal to the detector array surface. The beamformer section iscontrolled by a beamformer controller using a set of beamformerparameters. The space that the receiver considers is divided into aseries of volume elements radiating from the detector array and calledbeams. The center of each volume element of a beam has the same twoangular coordinate and each volume element may have the same thicknessas a slice. The beam volume elements may also preferably have thicknessproportional to their range from the detector, or any othercharacteristic parameters as chosen by a beamformer controller. Therange resolution is given by the slice thickness.

The beamformer controller controls the volume of space “seen” by thedetector array and used to collect data. For example, if the sonartransmitter sends out a narrow or a broad beam, or changes the directionof the sent out beam, the beamformer may also change the system to onlylook at the ensonified volume. Thus, the system of the inventionpreferably changes two or more of the system parameters between the samepings to improve the results. Some of the parameters controlled by thebeamformer controller are:

-   -   Field-of-view    -   Minimum and maximum beamformed ranges    -   Beam detection mode such as (First Above Threshold FAT or        maximum amplitude (MAX) or many other modes as known in the art)    -   Range resolution    -   Minimum signal level included in image    -   Image dynamic range    -   Array weighting function (used to modify the beamforming        profile)    -   Applying additional gain post beamforming (this can be        incorporated with Thresholding).

The incoming digital data stream from each sonar detector of thereceiver array has typically been multiplied by a TVG function. Atriangular data function ensures that the edges of the slices havelittle intensity to reduce digital noise in the signal. The TVG signalis set to zero to remove data that is collected from too near too and tofar away from the detector, and to increase or decrease the signaldepending on the situation.

In the prior art, the data have been filtered according to a criterion,and just one volume element for each beam was selected to have a value.For example, if the data was treated to accept the first signal in abeam arriving at the detector having an amplitude above a definedthreshold (FAT), the three dimension point cloud used to generate animage for the ping would be much different from a point cloud generatedby picking a value generated by using the maximum signal (MAX). In theFAT case, the image would be, for example, of fish swimming through theinsonified volume and the image in the MAX case would be the image ofthe sea bottom. In the prior art, only one range in each beam would showat most one value or point and all the other ranges of a single beamwould be assigned a zero.

In the present invention, the data stream is analyzed by completing twoor more beamformer processing procedures in the time between two pings,either in parallel or in series. In a video presentation, the prior artshowed a time series of 3D images to introduce another, fourth dimensiontime into the presentation of data. By introducing values into more thanone volume element per ping, we introduce a 5^(th) dimension to thepresentation. We can “see” behind objects, for example and “through”objects and “around” objects to get much more information. We can usevarious data treatments to improve the video image stream. In the sameway, other ways of analyzing the data stream can be used to accomplishprovide cleaner images, higher resolution images, expanded range images,etc. These different images imaging tasks to can be used on only oneping. The different images may be combined into a single image in avideo presentation, or in more than one video at the frame rate the sameas the ping rate.

If we are surveying a seawall, we Beamform the data before the wall (seabottom—oblique to beams (low backscatter) soft (low intensity signalsreturned)) differently from the harbour wall (orthogonal to beams (highback scatter) hard, high intensity. If we know where a seawall is from achart, the beamformer can use GPS or camera data to work out what rangesare before the wall and what are after and change TVG in the middle ofthe returned ping.

If we know the sea depth we can specify two planes, SeaSurfacePlane andSeatBottomPlane only data between the planes will be processed and sentfrom the head to the top end.

A large amount of data generated per second by prior art sonar systemshas traditionally been discarded because of data transmission and/orstorage limits. The present invention allows a higher percentage of theoriginal data generated to be stored for later analysis. The presentinvention makes use of a prior invention (U.S. application Ser. No.15/908,395 filed Feb. 28, 2018) assigned to the assignee of the presentinvention. In this invention, the raw data is not digitized by usinganalogue to digital circuitry, but by comparator technology whichdrastically reduces the equipment cost for the large sonar arrays used.The amount of amount of raw data sent from the receiver to thebeamformer is drastically reduced, allowing the beamformer to producemore data than a single beamformer parameter set data per ping.

The method of the invention starts the process of sending out a ping -bysetting all system parameters for all system controllers. Either allparameters are the same as the last ping, or they are changedautomatically by signals from stages of the previous ping. Commands aresent to the ping transmitter which sends data to the receiver controllerto set parameters for the receiver and start the receiver. Receiverreceives analogue signals, samples the voltages from each element, andtransmits data to the beamformer controller which sends data andinstructions to the Beamformer section.

The beamformer analyses data and decides whether the next ping shouldchange settings, and if so sends signals to the appropriate controllerto change the settings for the next ping. The beamformer analyses thedata and decides either on the basis of incoming ping data or onprevious instructions whether to perform single or multiple types ofanalysis of the incoming ping data. For example, the beamformer couldanalyze the data using both the FAT and MAX analysis, and present bothimages either separately or combined, so that there will be some beamshaving more than one value per beam. The reduced data is stored or rawdata or image data is sent for further processing into a videopresentation at a rate greater than a preferred rate of 5 frames persecond. More preferably, a frame rate of 10 frames a second, and a mostpreferred frame rate of 20 frames per second has been shown.

Sonar imaging started with scanning an object to produce a sequence ofimages which could be used to produce a 3 dimensional (3D) shape. Thelimitation of this approach is the inability to see any moving objectsand the dependency of a stable platform to record perform the imaging.The Echoscope® was the world's first 3D sonar system that allowed movingobjects in the water column to be viewed in real time, making it thefirst truly four-dimensional sonar system. 4D volumetric imagesrepresent a true volume of spatial data collected and processed at thesame instant. Sequential 4D volumetric images represent a time sequenceof the scene showing moving objects within the volumetric image.

The Echoscope's® video quality imaging has continued to lead the fieldfor over two decades. Coda Octopus are now achieving another worldfirst: bringing to the market the world's first 5D and 6D Sonars.

5D images are 4D images with multiple slices of depth data, similar to amedical CT scan. The 5 D images contain more depth information, detail,and resolution of each target and sequential 5CD images over time showhigher resolution moving targets.

6D Parallel Intelligent Processing Engine (PIPE) allows multipleparallel 5D images to be generated with different imaging and sonarparameters. This allows different processing to be performed on rawsonar data in parallel to extract more specific results withoutcompromise.

The original Echoscope® system, first released in 2004, revolutionised3D sonar by simultaneously beamforming a grid of over 16,000 beams,allowing a full 3D depth image to be generated in under 1/10^(th) of asecond. This rapid processing allowed the system to deliver theEchoscope's trademark real-time 3D output, generating video quality, 3Dviews of moving objects in the water column. The ability to presentthese 3D maps in real time means that the existing Echoscope is alreadya 4D system, and it is this fourth dimension of time that continues todifferentiate the Echoscope from its competitors.

CodaOctopus has continued to push the technological boundaries, and arereleasing a series of new 5G and 6G sonars that are set to dramaticallyextend the capability of the Echoscope®. At the heart of this new systemis a state-of-the art processor that allows the sonar data to be handledorders of magnitude faster, and with much greater flexibility, or storedfor off-line processing. The biggest change facilitated by thisprocessor is the ability to beamform the entire duration of each sonarping to give full time series (FTS) data on all beams. Rather than justreturning at most a single 1 dimensional range point for each beam tocreate an image with a maximum 16,384 points), the new system returns afully populated volume of over 1.6 million beamformed data points, whilestill operating at over 20 pings per second!

The ability to return multiple data points on every beam takes the datato the next generation and presents a wealth of new opportunities foranalysing the sonar data. The biggest initial advantage is that the 5Gsystem generates much fuller, and more detailed images when the pointsare rendered in 3D, as the beamformer can potentially see around smallerobjects in the near-field. The system also returns multiple range pointsfor beams striking flat surfaces at high incidence angles, meaning thatthe seafloor is much better resolved in the far field of the volumeimage.

The state-of-the-art processor has also allowed the sensitivity of thebeamformer to be increased, as its floating-point operation allows for amuch greater dynamic range in the data. This is a significant advantagein many acoustically challenging applications and environments. Thecombination of having multiple range points recorded for each beam andthe increase in sensitivity means that the far-field can be much moreclearly and densely resolved in the output images.

The major increase in the quality and volume of data generated by the 5Gsystem means that new types of data processing are possible, and new,useful information can be extracted. The challenge with large datasets,however, is that they can be slow and cumbersome to analyse. To combatthis Coda Octopus have developed PIPE®: The Parallel InformationProcessing Engine. This tool adopts novel parallel processing methods toperform multiple, simultaneous analyses of the large 5G dataset,delivering a range of useful outputs in real time. This ability toproduce multiple, concurrent 5GD datasets takes the new system to itssixth data generation (6G).

The development of PIPE® is not just restricted to the data processingside of the system, with hardware updates also being implemented tomaximise the functionality of this new tool. Different 5G data outputsmight require different signals to be transmitted from the sonar, ormight need different signal amplification and filtering operations to beapplied. For example, one task might need high-resolution and a narrowfield of view, while another could require a low-frequency, long rangesignal with a wide field of view. PIPE allows these different 5Gdatasets to be processed concurrently by switching between manydifferent sets of sonar operating parameters, with this switchingoccurring from ping to ping at 20 Hz. It is possible, for example, togenerate four completely different 5G sonar images separated by lessthan 0.05 sec , with the composite, 6G image being fully updated 5 timesper second.

To understand the full potential of this new technology, consider a pipeinspection operation being conducted with an ROV. The ROV pilot requiresa longer range, forward looking view to allow both navigation andobstacle avoidance. There could then be an engineer inspecting thecondition of the pipe itself, who requires a high resolution, downwardlooking image to be able to detect damage or corrosion on the pipe. The6G PIPE system is capable of generating both these images simultaneouslyin real time, meaning that the engineers are able to make instantdecisions, such as whether to slow down to inspect a particular sectionof pipe in more detail.

Since the raw data from the survey is also being stored, it is possibleto go back through the data in post-processing and apply different imageprocessing methods to highlight different information. This does notprovide quite the same flexibility as the real-time 6G processing, asthe transmit and receive parameters are fixed. There is stillsignificant value, however, in having access to the measured raw datarather than a processed image that has already removed a largeproportion of the original information.

In the case study presented above, all the different presentations ofthe data were being viewed by human analysts, but this doesn't have tobe the case: the new 5D/6D data makes the latest generation Echoscopevery well suited to deployment on a fully autonomous vehicle. As anexample, the system could be operated to simultaneously provide afar-field obstacle avoidance view, and a high-resolution seabed view fordetailed autonomous navigation. The raw data could then be stored forsubsequent human post-processing and analysis once the AUV is returnedto the surface.

The Echoscope 5G/6G system is the sonar for the information age. It usesthe very latest hardware and software to open up a range of newpossibilities for visualising and analysing the underwater environment.The 5D/6G system is also ideally placed to satisfy the future needs ofthe growing fleet of autonomous vessels in the world's oceans, lakes andrivers. It therefore looks likely that the new generation of CodaOctopus 5G/6G Echoscopes will continue to lead the field, as their 4Gpredecessors have done before them.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

1. A method of recording sonar data measured by a sonar system havingsonar system parameters, comprising; a) transmitting a first set ofsonar pings into a first volume of sonar signal transmitting material,the sonar pings transmitted from a sonar ping transmitting device,wherein the sonar ping transmitting device is controlled by a first setof ping transmitting parameters chosen from a predetermined list of pingtransmitting parameters; b) receiving sonar acoustical signals reflectedor scattered from objects in the first volume of sonar signaltransmitting material, wherein the received acoustical sonar signals arereceived by a sonar receiving device array controlled by a first set ofreceiver parameters selected from a predetermined list of receiverparameters to convert the received sonar acoustical signals into digitaldata signals which are transmitted to a sonar beamforming device and/ora digital processing device for further processing of the digital datasignals, c) beamforming and/or further processing the received sonarsignals wherein the step of sonar beamforming is performed by a sonarbeamforming device controlled by a first set of beamforming parameterschosen from a predetermined list of beamforming parameters, and whereinthe digital processing device for further processing is controlled byparameters chosen from a predetermined list of processing deviceparameters; then d) changing at least one sonar system parameter toprovide at least two significantly different three dimensional (3D)sonar data sets for each ping of the first set of pings, the at leasttwo (3D) sonar data sets for describing the objects reflecting orscattering the transmitted sonar signals, wherein a sonar systemparameter is defined as any parameter chosen from the predeterminedlists of ping transmitting parameters, receiver parameters, beamformingparameters, and processing device parameters.
 2. The method of claim 1,wherein the at least two significantly different sonar data sets areused to provide at least two significantly different beamformed sonarimages.
 3. The method of claim 2, wherein step d) further compriseschanging at least one of the sonar beamforming device parameters foreach ping of the first set of pings during the step of beamforming. 4.The method of claim 1, wherein step d) further comprises; changing atleast one of the sonar receiving device parameters during the step ofreceiving for each ping of the first set of pings.
 5. The method ofclaim 4, wherein two different gain profiles are used to provide twosignificantly different data sets for each ping of the first set ofpings.
 6. The method of claim 1, wherein the sonar system parameters areset to provide sonar data to reconstruct a consolidated image from therequested eyepoints of a more than one user.
 7. The method of claim 1,wherein the image resolution is changed during the sonar signalreceiving step from higher resolution for the first arriving pingreflection to lower resolution for the later arriving ping reflections.8. The method of claim 1, wherein features identified in two or moredata sets for each ping are matched with corresponding featuresidentified in at least one further data set to provide a mosaic database.
 9. The method of claim 8, wherein the at least one further dataset for a ping is produced from preceding and/or succeeding pings, andwhere in the sonar device parameter changed is a digital processingdevice parameter, wherein the digital processing device parameterchanged is a sidelobe clipping parameter and/or a thresholdingparameter.
 10. The method of claim 9, wherein the at least one digitalprocessing device parameter changed is chosen to reduce unwantedacoustic artefacts.
 11. The method of claim 1, wherein one of the atleast two significantly different sonar data sets for each ping of thefirst set of pings is a full-time series 3D volume data set or a partialseries 3D volume data set.
 12. The method of claim 11, wherein two ofthe at least two significantly different sonar data sets are a full-timeseries 3D volume data set and a partial series 3D volume data set. 13.The method of claim 1, wherein the at least one digital processingdevice parameter is changed from a first sidelobe filter to a secondsidelobe filter.
 14. The method of claim 13, wherein the sonar data setproduced using the first sidelobe filter is monitored in real-time toensure no wanted objects are being removed.
 15. The method of claim 1,wherein the image resolution is changed during the sonar signalreceiving step from higher resolution for the first arriving pingreflection to lower resolution for the later arriving ping reflections.16. The method of claim 1, wherein features identified in the two ormore data sets are matched with a Simultaneous Localization and Mapping(SLAM) technique.
 17. The method of claim 1, wherein an absolutelypositioned mosaic is created.
 18. The method of claim 17, wherein thetwo or more data sets for each ping are matched with models.
 19. Themethod of claim 18, wherein the models represent known physicalentities.
 20. The method of claim 18, wherein the models may be movingand/or updated in real-time.
 22. The method of claim 18, wherein themodels are volume 3D binned data
 23. The method of claim 1, wherein thetwo or more data sets for each ping are compared with at least onepreviously generated data set.
 24. The method of claim 23, wherein thepreviously generated data set may be from a previous survey of the samephysical location.
 25. The method of claim 24, wherein the comparison isused to determine dredging progress and/or to check for scouring aroundstructures in areas with high underwater currents and/or to check forchanges in infrastructure.
 26. The method of claim 23, wherein the twoor more data sets for each ping are matched with data from previouslysurveyed areas to find to determine dredging progress and/or to checkfor scouring around structures in areas with high underwater currentsand/or to check for changes in infrastructure such as quay wall damageand/or explosive devices placed underwater.
 27. The method of claim 1,wherein the range of at least one of the at least two significantlydifferent data sets is divided into a number of sections, and the rangeof zero or one object for each section is recorded and/or shown as apartial time-series.
 28. The method of claim 27, wherein at least one ofat least two significantly different beamformed sonar images is a customview.
 29. The method of claim 28, wherein the custom view is a crosssection or a plan view.
 30. The method of claim 1, wherein the first setof sonar pings forms part of a series of sets of sonar pings transmittedat a rate of at least 5 pings per second.
 31. The method of claim 30,wherein the least two significantly different sonar data setsrepresentative of the first set of sonar pings are displayed as at leastone video stream at a frame rate of at least 5 frames per second. 32.The method of claim 30, wherein two sets of sonar data are recordedand/or shown.
 33. The method of claim 1, wherein at least twosignificantly different sonar data sets for each ping of the first setof pings are used to simultaneously provide a far-field obstacleavoidance view and a high-resolution seabed view.
 34. The method ofclaim 33, wherein the far-field obstacle avoidance view and thehigh-resolution seabed view are used in autonomous navigation.
 35. Themethod of claim 1, wherein at least one of the at least twosignificantly different sonar data sets for each ping comprises rawdata.